If you want to add more performance to your Mercury Mountaineer a K&N performance air filter will do the job. K&N air filters use a washable and reusable filter element that out flows your factory Mercury Mountaineer air filter. K&N air filters are the industry standard in performance filters and Slickcar.com offers a complete line for your Mountaineer. With the Million Mile guarantee you will never need to buy another air filter for your Mercury Mountaineer . If you canít find the correct K&N performance filter for your Mercury please call us toll free at 1-800-780-1409.